Substrate processing apparatus, mixing method, and substrate processing method

ABSTRACT

A substrate processing apparatus includes a processing bath, a mixing device, a liquid path, and a silicon solution supply. A substrate is immersed in the processing bath to be processed. The mixing device generates a mixture liquid by mixing a phosphoric acid aqueous solution with an additive that suppresses precipitation of silicon oxide. The liquid path sends the mixture liquid from the mixing device to the processing bath. The silicon solution supply is connected to at least one of the liquid path and the processing bath, and supplies a silicon-containing compound aqueous solution to the mixture liquid supplied from the mixing device.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application is based on and claims priority from Japanese PatentApplication Nos. 2019-048845 and 2020-000624 filed on Mar. 15, 2019 andJan. 7, 2020, respectively, with the Japan Patent Office, thedisclosures of which are incorporated herein in their entireties byreference.

TECHNICAL FIELD

The present disclosure relates to a substrate processing apparatus, amixing method, and a substrate processing method.

BACKGROUND

In a substrate processing system, it has been known that an etchingprocessing is performed on a substrate by immersing such a substrate inan etching liquid including a phosphoric acid aqueous solution and asilicon solution (see Japanese Patent Laid-Open Publication No.2017-118092).

SUMMARY

According to an aspect of the present disclosure, a substrate processingapparatus includes a processing bath, a mixing device, a liquid sendingpath, and a silicon solution supply. The processing bath processes asubstrate through immersion. The mixing device generates a mixtureliquid by mixing a phosphoric acid aqueous solution with an additivethat suppresses precipitation of silicon oxide. The liquid sending pathsends the mixture liquid from the mixing device to the processing bath.The silicon solution supply is connected to at least one of the liquidsending path and the processing bath, and supplies a silicon-containingcompound aqueous solution to the mixture liquid supplied from the mixingdevice.

The foregoing summary is illustrative only and is not intended to be inany way limiting. In addition to the illustrative aspects, embodiments,and features described above, further aspects, embodiments, and featureswill become apparent by reference to the accompanying drawings and thefollowing detailed description.

BRIEF DESCRIPTION OF THE DRAWINGS

FIG. 1 is a schematic block diagram illustrating the configuration of asubstrate processing system according to an embodiment.

FIG. 2 is a timing chart illustrating a specific example of a behaviorpattern of each unit in the substrate processing system, during variousprocesses when a mixture liquid is initially sent to a processing bathaccording to the embodiment.

FIG. 3 is a timing chart illustrating a specific example of a behaviorpattern of each unit in the substrate processing system, during variousprocesses when the silicon concentration of an etching liquid isadjusted in the processing bath according to the embodiment.

FIG. 4 is a schematic block diagram illustrating a configuration of thesubstrate processing system according to a first modification of theembodiment.

FIG. 5 is a schematic block diagram illustrating a configuration of thesubstrate processing system according to a second modification of theembodiment.

FIG. 6 is a schematic block diagram illustrating a configuration of thesubstrate processing system according to a third modification of theembodiment.

FIG. 7 is a timing chart illustrating a specific example of a behaviorpattern of each unit in the substrate processing system, during variousprocesses when the mixture liquid is initially sent to the processingbath according to the third modification of the embodiment.

FIG. 8 is a timing chart illustrating a specific example of a behaviorpattern of each unit in the substrate processing system, during variousprocesses when the silicon concentration of the etching liquid isadjusted in the processing bath according to the third modification ofthe embodiment.

FIG. 9 is a schematic block diagram illustrating a configuration of thesubstrate processing system according to a fourth modification of theembodiment.

FIG. 10 is a view illustrating a specific example of the processing flowof a plurality of etching liquid supplies according to the fourthmodification of the embodiment.

FIG. 11 is a schematic block diagram illustrating a configuration of thesubstrate processing system according to a fifth modification of theembodiment.

FIG. 12 is a view illustrating a specific example of the processing flowof a plurality of etching liquid supplies according to the fifthmodification of the embodiment.

FIG. 13 is a schematic block diagram illustrating a configuration of thesubstrate processing system according to a sixth modification of theembodiment.

FIG. 14 is a view illustrating a specific example of the processing flowof a plurality of etching liquid supplies according to the sixthmodification of the embodiment.

FIG. 15 is a flow chart illustrating a processing procedure of a mixingprocess and a substrate processing according to the embodiment.

FIG. 16 is a flow chart illustrating a processing procedure of a mixingprocess and a substrate processing according to the third modificationof the embodiment.

DESCRIPTION OF EMBODIMENT

In the following detailed description, reference is made to theaccompanying drawings, which form a part thereof. The illustrativeembodiments described in the detailed description, drawings, and claimsare not meant to be limiting. Other embodiments may be utilized, andother changes may be made without departing from the spirit or scope ofthe subject matter presented here.

Hereinafter, embodiments of a substrate processing apparatus, a mixingmethod, and a substrate processing method according to the presentdisclosure will be described in detail with reference to accompanyingdrawings. The present disclosure is not limited by the embodiment to bedescribed below. It should be noted that the drawings are schematic, andfor example, a dimensional relationship of elements, and a ratio of theelements are different from actual ones in some cases. Further, in somecases, the drawings may include portions which are mutually differentfrom each other in the dimensional relationship or the ratio.

In a substrate processing system, it has conventionally been known thatan etching processing is performed on a substrate by immersing such asubstrate in an etching liquid including a phosphoric acid aqueoussolution and a silicon solution.

For example, by immersing the substrate in the phosphoric acid (H₃PO₄)aqueous solution, it is possible to selectively etch a silicon nitridefilm between the silicon nitride film (SiN) and a silicon oxide film(SiO₂) laminated on the substrate.

By adding the silicon solution (a silicon-containing compound aqueoussolution) to the phosphoric acid aqueous solution, it is possible toimprove the etching selectivity of the silicon nitride film to thesilicon oxide film.

Meanwhile, when the silicon nitride film is etched, silicon contained insuch a silicon nitride film is eluted into the etching liquid. Thus, insome cases, a silicon concentration in the phosphoric acid aqueoussolution becomes excessive.

Then, when the silicon concentration in the phosphoric acid aqueoussolution becomes excessive, silicon oxide (SiO₂) is deposited on thesilicon oxide film, and there is a concern that an etching processing ofthe substrate may be suppressed due to such deposited silicon oxide.

Therefore, a technology in which it is possible to properly perform anetching processing by an etching liquid containing a phosphoric acidaqueous solution and a silicon solution is expected.

<Configuration of Substrate Processing System>

First, the configuration of a substrate processing system 1 according toan embodiment will be described with reference to FIG. 1. FIG. 1 is aschematic block diagram illustrating the configuration of the substrateprocessing system 1 according to the embodiment. The substrateprocessing system 1 is an example of a substrate processing apparatus.

The substrate processing system 1 includes a mixing device 10, a siliconsolution supply 25, and a substrate processor 30. The mixing device 10generates a mixture liquid M by mixing a phosphoric acid aqueoussolution with a precipitation inhibitor that suppresses precipitation ofsilicon oxide. The precipitation inhibitor is an example of an additive.

The silicon solution supply 25 supplies a silicon-containing compoundaqueous solution (hereinafter, also referred to as a silicon solution)to the mixture liquid M generated by the mixing device 10 so as togenerate an etching liquid E. That is, the etching liquid E according tothe embodiment contains the phosphoric acid aqueous solution, theprecipitation inhibitor, and the silicon solution.

The substrate processor 30 performs an etching processing on a wafer Wby immersing such a wafer W in the generated etching liquid E in aprocessing bath 31. The wafer W is an example of a substrate. In theembodiment, for example, it is possible to selectively etch a siliconnitride film between the silicon nitride film (SiN) and a silicon oxidefilm (SiO₂) formed on the wafer W.

The mixing device 10 includes a phosphoric acid aqueous solution supply11, a precipitation inhibitor supply 12, a tank 14, and a circulationpath 15.

The phosphoric acid aqueous solution supply 11 supplies the phosphoricacid aqueous solution to the tank 14. This phosphoric acid aqueoussolution supply 11 includes a phosphoric acid aqueous solution supplysource 11 a, a phosphoric acid aqueous solution supply path 11 b, and aflow rate regulator 11 c.

The phosphoric acid aqueous solution supply source 11 a is, for example,a tank that stores the phosphoric acid aqueous solution. The phosphoricacid aqueous solution supply path 11 b connects the phosphoric acidaqueous solution supply source 11 a to the tank 14, and supplies thephosphoric acid aqueous solution from the phosphoric acid aqueoussolution supply source 11 a to the tank 14.

The flow rate regulator 11 c is provided in the phosphoric acid aqueoussolution supply path 11 b, and adjusts the flow rate of the phosphoricacid aqueous solution to be supplied to the tank 14. The flow rateregulator 11 c is constituted by, for example, an open/close valve, aflow rate control valve, or a flow meter.

The precipitation inhibitor supply 12 supplies the precipitationinhibitor to the tank 14. This precipitation inhibitor supply 12includes a precipitation inhibitor supply source 12 a, a precipitationinhibitor supply path 12 b, and a flow rate regulator 12 c.

The precipitation inhibitor supply source 12 a is, for example, a tankthat stores the precipitation inhibitor. The precipitation inhibitorsupply path 12 b connects the precipitation inhibitor supply source 12 ato the tank 14, and supplies the precipitation inhibitor from theprecipitation inhibitor supply source 12 a to the tank 14.

The flow rate regulator 12 c is provided in the precipitation inhibitorsupply path 12 b, and adjusts the flow rate of precipitation inhibitorto be supplied to the tank 14. The flow rate regulator 12 c isconstituted by, for example, an open/close valve, a flow rate controlvalve, or a flow meter.

The precipitation inhibitor according to the embodiment only has tocontain a component that suppresses precipitation of silicon oxide. Forexample, the precipitation inhibitor may contain a component thatstabilizes silicon ions dissolved in the phosphoric acid aqueoussolution in a dissolved state and suppresses the precipitation ofsilicon oxide. Further, the precipitation inhibitor may contain acomponent that suppresses the precipitation of silicon oxide by otherknown methods.

As for the precipitation inhibitor according to the embodiment, forexample, a hexafluorosilicic acid (H₂SiF₆) aqueous solution containing afluorine component may be used. An additive such as ammonia may becontained in order to stabilize hexafluorosilicic acid in the aqueoussolution.

As for the precipitation inhibitor according to the embodiment, forexample, ammonium hexafluorosilicate (NH₄)₂SiF₆, or sodiumhexafluorosilicate (Na₂SiF₆) may be used.

The precipitation inhibitor according to the embodiment may be acompound containing an element that is a cation having an ion radiusranging from 0.2□ to 0.9□. Here, the “ion radius” is a radius of an ionempirically found from the sum of radii of an anion and a cation, whichis obtained from a lattice constant of a crystal lattice.

The precipitation inhibitor according to the embodiment may containoxide of any one of elements, for example, aluminum, potassium, lithium,sodium, magnesium, calcium, zirconium, tungsten, titanium, molybdenum,hafnium, nickel and chromium.

The precipitation inhibitor according to the embodiment may contain atleast one of nitride, chloride, bromide, hydroxide and nitrate of theabove described one element, instead of or in addition to the abovedescribed oxide of any one element.

The precipitation inhibitor according to the embodiment may contain atleast one of, for example, Al(OH)₃, AlCl₃, AlBr₃, Al(NO₃)₃, Al₂(SO₄)₃,AlPO₄ and Al₂O₃.

The precipitation inhibitor according to the embodiment may contain atleast one of KCl, KBr, KOH and KNO₃. The precipitation inhibitoraccording to the embodiment may contain at least one of LiCl, NaCl,MgCl₂, CaCl₂ and ZrCl₄.

The tank 14 stores the phosphoric acid aqueous solution supplied fromthe phosphoric acid aqueous solution supply 11, and the precipitationinhibitor supplied from the precipitation inhibitor supply 12. Also, thetank 14 stores the mixture liquid M generated by mixing the phosphoricacid aqueous solution with the precipitation inhibitor.

The tank 14 is provided with a first liquid level sensor S1 and a secondliquid level sensor S2 in order from top. This controls the height of aliquid level of the phosphoric acid aqueous solution or the mixtureliquid M stored in the tank 14. In the embodiment, by using the firstliquid level sensor S1 and the second liquid level sensor S2, it ispossible to measure the liquid volume of the phosphoric acid aqueoussolution or the precipitation inhibitor.

The circulation path 15 is a circulation line that exits from the tank14, and returns to the tank 14. The circulation path 15 has an inlet 15a provided at the bottom of the tank 14 and an outlet 15 b provided atthe top of the tank 14, and forms a circulating flow that flows from theinlet 15 a toward the outlet 15 b. In the embodiment, the outlet 15 b isdisposed above the liquid level of the mixture liquid M stored in thetank 14.

In the circulation path 15, a pump 16, a heater 17, an open/close valve18, a filter 19, and a diverging portion 15 c are provided in order fromthe upstream side with respect to the tank 14. A liquid sending path 22that sends the mixture liquid M to the processing bath 31 of thesubstrate processor 30 diverges from the diverging portion 15 c.

The liquid sending path 22 is connected from the diverging portion 15 cto an inner tank 31 a and an outer tank 31 b of the processing bath 31,and includes a flow rate regulator 23. The flow rate regulator 23adjusts the flow rate of the mixture liquid M to be supplied to theprocessing bath 31. The flow rate regulator 23 is constituted by, forexample, an open/close valve, a flow rate control valve, or a flowmeter.

The pump 16 forms a circulating flow of the mixture liquid M that exitsfrom the tank 14, and returns to the tank 14 through the circulationpath 15.

The heater 17 heats the mixture liquid M circulating in the circulationpath 15. In the embodiment, the heater 17 heats the mixture liquid M,thereby heating the mixture liquid M stored in the tank 14.

The filter 19 removes contaminants such as particles included in themixture liquid M circulating in the circulation path 15. A bypass flowpath 20 that bypasses the filter 19 is provided in the circulation path15, and an open/close valve 21 is provided in the bypass flow path 20.

Then, by alternately opening/closing the open/close valve 18 provided inthe circulation path 15 and the open/close valve 21 provided in thebypass flow path 20, it is possible to form any one of a circulatingflow flowing through the filter 19, and a circulating flow bypassing thefilter 19.

The silicon solution supply 25 supplies the silicon solution to themixture liquid M generated by the mixing device 10. The silicon solutionaccording to the embodiment is a solution in which, for example,colloidal silicon is dispersed. The silicon solution supply 25 includesa silicon solution supply source 25 a, a silicon solution supply path 25b, and a flow rate regulator 25 c.

The silicon solution supply source 25 a is, for example, a tank thatstores the silicon solution. The flow rate regulator 25 c is provided inthe silicon solution supply path 25 b, and adjusts the flow rate of thesilicon solution flowing through the silicon solution supply path 25 b.The flow rate regulator 25 c is constituted by, for example, anopen/close valve, a flow rate control valve, or a flow meter.

Here, in the embodiment, the silicon solution supply path 25 b of thesilicon solution supply 25 is connected to a junction 22 a provided inthe liquid sending path 22. That is, in the embodiment, after themixture liquid M is generated by the mixing device 10, the siliconsolution may be individually supplied to the generated mixture liquid Mto generate the etching liquid E.

Accordingly, it is possible to adjust the silicon concentration in themixture liquid M to be supplied to the substrate processor 30, in a widerange. Next, a method of adjusting the silicon concentration in themixture liquid M will be described with reference to FIG. 2 and FIG. 3.

FIG. 2 is a timing chart illustrating a specific example of a behaviorpattern of each unit in the substrate processing system 1, duringvarious processes when the mixture liquid M is initially sent to theprocessing bath 31 according to the embodiment. Each unit of thesubstrate processing system 1 is controlled by a controller (notillustrated) provided in the substrate processing system 1.

Such a controller controls the operation of each unit (for example, themixing device 10 or the substrate processor 30) of the substrateprocessing system 1 illustrated in FIG. 1. The controller controls theoperation of each unit of the substrate processing system 1 based onsignals from, for example, a switch or various sensors.

The controller is, for example, a computer, and has a computer-readablestorage medium (not illustrated). Such a storage medium stores a programthat controls various processes to be executed in the substrateprocessing system 1.

The controller controls the operation of the substrate processing system1, by reading and executing the program stored in the storage medium.The program, which is stored in the computer-readable storage medium,may have been installed from another storage medium to the storagemedium of the controller.

Examples of the computer-readable storage medium include a hard disk(HD), a flexible disk (FD), a compact disc (CD), a magneto-optical disk(MO), and a memory card.

As illustrated in FIG. 2, in the embodiment, a mixing process, a heatingprocess, a filtration process, and a liquid sending process aresequentially performed. First, the controller starts the mixing processby operating (turning ON) the phosphoric acid aqueous solution supply 11from time T0, and supplying the phosphoric acid aqueous solution to thetank 14.

At this point in time T0, the precipitation inhibitor supply 12, thesilicon solution supply 25, the pump 16, and the heater 17 are notoperating (OFF state). At the point in time T0, since the open/closevalve 18 is in a close state and the open/close valve 21 is in an openstate, in this state, the filter 19 is bypassed by the bypass flow path20 (a filter bypass is in an ON state).

At the point in time T0, the flow rate regulator 23 is in a close state(OFF state), and OFF signals are output from the first liquid levelsensor S1 and the second liquid level sensor S2 since nothing is storedin the tank 14.

Then, the liquid level of the phosphoric acid aqueous solution stored inthe tank 14 gradually rises. When the liquid level becomes equal to orhigher than a predetermined second height at time T1, an ON signal isoutput from the second liquid level sensor S2.

Then, the controller supplies the precipitation inhibitor to the tank 14by operating (turning ON) the precipitation inhibitor supply 12 fromtime T1. The controller forms a circulating flow in the circulation path15 by operating (turning ON) the pump 16 from time T1.

Next, at time T2 when the precipitation inhibitor has been supplied in apredetermined amount to the tank 14, the controller stops (turns OFF)the precipitation inhibitor supply 12.

Next, at time T3, when the liquid level of the mixture liquid M becomesequal to or higher than a predetermined first height, an ON signal isoutput from the first liquid level sensor S1. Then, the controllerconsiders that the phosphoric acid aqueous solution has been supplied ina predetermined amount to the tank 14, and stops (turns OFF) thephosphoric acid aqueous solution supply 11 at time T3. Accordingly, themixing process is completed.

Next, the controller starts the heating process by operating (turningON) the heater 17 from time T3, and heating the mixture liquid Mcirculating in the circulation path 15. The controller heats the mixtureliquid M by the heater 17, thereby heating the mixture liquid M storedin the tank 14.

In the embodiment, the liquid volume of, for example, the phosphoricacid aqueous solution is measured by using, for example, the firstliquid level sensor S1, but, in some cases, a temperature change of thestored mixture liquid M may adversely affect the accuracy ofmeasurement.

Therefore, in the embodiment, the heating process is started from thepoint in time (time T3) when the measurement of, for example, thephosphoric acid aqueous solution is completed, and the mixing process iscompleted. Accordingly, it is possible to satisfactorily maintain themeasurement accuracy of, for example, the phosphoric acid aqueoussolution.

Next, at time T4 when the mixture liquid M within the tank 14 is heatedto a predetermined temperature (for example, less than 100° C.), theheating process is completed. As described above, in the embodiment, itis possible to supply the heated mixture liquid M to the substrateprocessor 30 by providing the heater 17 that performs the heatingprocess, in the mixing device 10.

In the embodiment, it is possible to efficiently heat the mixture liquidM by providing the heater 17 in the circulation path 15 of the mixingdevice 10.

In the substrate processing according to the embodiment, the heatingprocess starts after the mixing process is completed. This is because ifthe precipitation inhibitor containing an organic solvent is supplied tothe phosphoric acid aqueous solution whose temperature has risen byheating, there is a concern that such a precipitation inhibitor may bebumped.

That is, according to the embodiment, it is possible to suppress theprecipitation inhibitor from being bumped during the supply by startingthe heating process after the mixing process is completed.

Next, the controller starts the filtration process by turning OFF thefilter bypass from time T4. That is, from time T4, the controllerchanges the open/close valve 18 to an open state and changes theopen/close valve 21 to a close state, so as to form a circulating flowflowing through the filter 19, in the circulation path 15. Accordingly,contaminants such as particles contained in the mixture liquid M areremoved.

Then, the filtration process is completed at time T5 when thecontaminants such as particles contained in the mixture liquid M aresufficiently removed.

In the substrate processing according to the embodiment, the filterbypass is turned ON in the mixing process and the heating process.Accordingly, since in the circulation path 15, a pressure loss occurringin the filter 19 may be reduced, it is possible to efficiently circulatethe mixture liquid M stored in the tank 14.

Since there is no need to filter the mixture liquid M with the filter 19until the heating process is completed, there is no particular problemeven if the mixture liquid M is circulated through the bypass flow path20.

Next, the controller starts the liquid sending process from time T5.

Specifically, the controller sends the silicon solution to theprocessing bath 31 of the substrate processor 30 through the liquidsending path 22 by operating (turning ON) the silicon solution supply 25from time T5.

The controller stops (turns OFF) the pump 16 at the same timing (timeT5) as the supply start of the silicon solution. Accordingly, it ispossible to suppress the mixture liquid M from flowing backward from theliquid sending path 22 to the silicon solution supply 25 due to a highpressure from the pump 16.

The controller stops (turns OFF) the heater 17 at the same timing (timeT5) as the supply start of the silicon solution. Accordingly, it ispossible to suppress the temperature of the mixture liquid M frombecoming higher than the predetermined temperature (for example, lessthan 100° C.).

Next, at time T6 when the silicon solution has been supplied in apredetermined amount to the processing bath 31, the controller stops(turns OFF) the silicon solution supply 25. Then, the controlleroperates (turns ON) the pump 16, and places (turns ON) the flow rateregulator 23 in an open state, at the same timing (time T6) as thesupply stop of the silicon solution.

Accordingly, the controller sends the mixture liquid M from the mixingdevice 10 to the processing bath 31 of the substrate processor 30through the circulation path 15 and the liquid sending path 22. Then,the mixture liquid M within the tank 14 is reduced, and the liquid levelbecomes lower than the predetermined first height at time T7.

Accordingly, an OFF signal is output from the first liquid level sensorS1. Then, at time T8 when the mixture liquid M has been sent in apredetermined amount, the liquid sending process is completed.

Through the processes described so far, the controller may store theetching liquid E having a desired silicon concentration, in theprocessing bath 31 when initially sending the mixture liquid M to theprocessing bath 31. Therefore, according to the embodiment, from thepoint in time when an etching processing on the wafer W is started, itis possible to improve the etching selectivity of the silicon nitridefilm to the silicon oxide film.

FIG. 3 is a timing chart illustrating a specific example of a behaviorpattern of each unit in the substrate processing system 1, duringvarious processes when the silicon concentration of the etching liquid Eis adjusted in the processing bath 31 according to the embodiment.

In FIG. 3, descriptions will be made on a mixing process to a liquidsending process of the mixture liquid M to be sent when silicon iseluted into the etching liquid E from the wafer W after the etchingprocessing on the wafer W is started in the processing bath 31.

First, the controller starts the mixing process by operating (turningON) the phosphoric acid aqueous solution supply 11 from time T10, andsupplying the phosphoric acid aqueous solution to the tank 14.

At this point in time T10, the precipitation inhibitor supply 12, thesilicon solution supply 25, the pump 16, and the heater 17 are notoperating (OFF state). At the point in time T10, since the open/closevalve 18 is in a close state and the open/close valve 21 is in an openstate, in this state, the filter 19 is bypassed by the bypass flow path20 (the filter bypass is in an ON state).

At the point in time T10, the flow rate regulator 23 is in a close state(OFF state), and OFF signals are output from the first liquid levelsensor S1 and the second liquid level sensor S2 since the amount of themixture liquid M has been reduced within the tank 14 by the previousliquid sending process.

Then, the liquid level of the phosphoric acid aqueous solution stored inthe tank 14 gradually rises. When the liquid level becomes equal to orhigher than the predetermined second height at time T11, an ON signal isoutput from the second liquid level sensor S2.

Then, the controller supplies the precipitation inhibitor to the tank 14by operating (turning ON) the precipitation inhibitor supply 12 fromtime T11. The controller forms a circulating flow in the circulationpath 15 by operating (turning ON) the pump 16 from time T11.

Next, at time T12 when the precipitation inhibitor has been supplied ina predetermined amount to the tank 14, the controller stops (turns OFF)the precipitation inhibitor supply 12.

Next, at time T13, when the liquid level of the mixture liquid M becomesequal to or higher than the predetermined first height, an ON signal isoutput from the first liquid level sensor S1. Then, the controllerconsiders that the phosphoric acid aqueous solution has been supplied ina predetermined amount to the tank 14, and stops (turns OFF) thephosphoric acid aqueous solution supply 11 at time T13.

Next, the controller starts the heating process by operating (turningON) the heater 17 from time T13, and heating the mixture liquid Mcirculating in the circulation path 15. The controller heats the mixtureliquid M by the heater 17, thereby heating the mixture liquid M storedin the tank 14.

Next, at time T14 when the mixture liquid M within the tank 14 is heatedto a predetermined temperature (for example, about 165° C.), the heatingprocess is completed.

Next, the controller starts the filtration process by turning OFF thefilter bypass from time T14. Accordingly, contaminants such as particlescontained in the mixture liquid M are removed.

Then, the filtration process is completed at time T15 when thecontaminants such as particles contained in the mixture liquid M aresufficiently removed.

Next, the controller starts the liquid sending process from time T15.Specifically, the controller places (turns ON) the flow rate regulator23 in an open state at time T15.

Accordingly, the controller sends the mixture liquid M from the mixingdevice 10 to the processing bath 31 of the substrate processor 30through the circulation path 15 and the liquid sending path 22. Then,the mixture liquid M within the tank 14 is reduced, and the liquid levelbecomes lower than the predetermined first height at time T16.

Accordingly, an OFF signal is output from the first liquid level sensorS1. Then, at time T17 when the mixture liquid M has been sent in apredetermined amount, the liquid sending process is completed.

Through the processes described so far, the controller may supply themixture liquid M that does not contain the silicon solution, to theprocessing bath 31. Accordingly, when silicon is eluted from the siliconnitride film within the wafer W and the silicon concentration in theetching liquid E becomes excessive, it is possible to quickly suppressthe silicon concentration in the etching liquid E to a predeterminedconcentration.

As described above, in the embodiment, the silicon solution may beindividually supplied to the generated mixture liquid M to generate theetching liquid E. Thus, it is possible to adjust the siliconconcentration in the mixture liquid M to be supplied to the substrateprocessor 30, in a wide range.

That is, when a predetermined silicon concentration is required for themixture liquid M (for example, when the liquid is initially sent), it ispossible to supply the mixture liquid M containing the silicon solution,to the processing bath 31 by operating the silicon solution supply 25.

Meanwhile, when a predetermined silicon concentration is not requiredfor the mixture liquid M (for example, when the silicon concentration isadjusted), it is possible to supply the mixture liquid M not containingthe silicon solution to the processing bath 31 by not operating thesilicon solution supply 25.

In the embodiment, the liquid sending path 22 is provided diverging fromthe circulation path 15. Accordingly, the mixture liquid M may be sentto the processing bath 31 by the pump 16 used at the time of the mixingprocess or the heating process. That is, in the embodiment, since thereis no need to provide a separate pump in the liquid sending path 22 forthe purpose of the liquid sending process of the mixture liquid M, it ispossible to send the mixture liquid M at a low cost.

In the embodiment, by controlling the heater 17, the temperature of themixture liquid M may be set based on whether to supply the siliconsolution to the mixture liquid M. For example, when the silicon solutionis supplied to the mixture liquid M (for example, when the liquid isinitially sent), the mixture liquid M is heated to a temperature lessthan 100° C. while when the silicon solution is not supplied to themixture liquid M (for example, when the silicon concentration isadjusted), the mixture liquid M is heated to a temperature of about 165°C.

Accordingly, when the silicon solution is supplied to the mixture liquidM, it is possible to suppress the silicon solution containing moisturefrom being exposed to a high temperature and being bumped. When thesilicon solution is not supplied to the mixture liquid M, it is possibleto suppress the temperature of the etching liquid E during theprocessing from being reduced due to the supply of the mixture liquid M.

Referring back to FIG. 1, descriptions on other portions in thesubstrate processing system 1 will be continued. The substrate processor30 performs the etching processing on the wafer W by immersing the waferW in the etching liquid E generated by the mixing device 10.

The substrate processor 30 includes the processing bath 31, acirculation path 32, a DIW supply 33, and an etching liquid drainagesection 34. The processing bath 31 includes the inner tank 31 a and theouter tank 31 b.

The top portion of the inner tank 31 a is open, and the etching liquid Eis supplied to the vicinity of the top portion. In the inner tank 31 a,a plurality of wafers W is immersed in the etching liquid E by asubstrate lift mechanism 35, and the etching processing is performed onthe wafers W. The substrate lift mechanism 35 is configured to bemovable up and down, and holds the wafers W aligned in the front andrear direction in a vertical posture.

The outer tank 31 b is provided around the top portion of the inner tank31 a, and the top portion thereof is open. Into the outer tank 31 b, theetching liquid E overflowing from the inner tank 31 a flows.

To the inner tank 31 a and the outer tank 31 b, the mixture liquid M issupplied from the mixing device 10 through the liquid sending path 22,and the silicon solution is supplied from the silicon solution supply 25through the liquid sending path 22. To the outer tank 31 b, deionizedwater (DIW) is supplied from the DIW supply 33.

The DIW supply 33 includes a DIW supply source 33 a, a DIW supply path33 b, and a flow rate regulator 33 c. The DIW supply 33 supplies DIW tothe outer tank 31 b for the purpose of replenishment of moistureevaporated from the heated etching liquid E.

The DIW supply path 33 b connects the DIW supply source 33 a to theouter tank 31 b, and supplies DIW at a predetermined temperature fromthe DIW supply source 33 a to the outer tank 31 b.

The flow rate regulator 33 c is provided in the DIW supply path 33 b,and adjusts a supply amount of DIW to be supplied to the outer tank 31b. The flow rate regulator 33 c is constituted by, for example, anopen/close valve, a flow rate control valve, or a flow meter. Byadjusting the supply amount of DIW by the flow rate regulator 33 c, thetemperature, the phosphoric acid concentration, the siliconconcentration, and the precipitation inhibitor concentration, in theetching liquid E, are adjusted.

A temperature sensor 36 and a phosphoric acid concentration sensor 37are provided in the outer tank 31 b. The temperature sensor 36 detectsthe temperature of the etching liquid E, and the phosphoric acidconcentration sensor 37 detects the phosphoric acid concentration of theetching liquid E. Signals generated by the temperature sensor 36 and thephosphoric acid concentration sensor 37 are transmitted to the abovedescribed controller.

The outer tank 31 b and the inner tank 31 a are connected by thecirculation path 32. One end of the circulation path 32 is connected tothe bottom of the outer tank 31 b, and the other end of the circulationpath 32 is connected to a processing liquid supply nozzle 38 provided inthe inner tank 31 a.

The circulation path 32 is provided with a pump 39, a heater 40, afilter 41, and a silicon concentration sensor 42 in order from the outertank 31 b side.

The pump 39 forms a circulating flow of the etching liquid E sent fromthe outer tank 31 b to the inner tank 31 a through the circulation path32. The etching liquid E flows out to the outer tank 31 b again byoverflowing from the inner tank 31 a. In this manner, the circulatingflow of the etching liquid E is formed within the substrate processor30. That is, such a circulating flow is formed in the outer tank 31 b,the circulation path 32, and the inner tank 31 a.

The heater 40 adjusts the temperature of the etching liquid Ecirculating in the circulation path 32. The filter 41 filters theetching liquid E circulating in the circulation path 32. The siliconconcentration sensor 42 detects the silicon concentration in the etchingliquid E circulating in the circulation path 32. A signal generated bythe silicon concentration sensor 42 is transmitted to the controller.

The etching liquid drainage section 34 discharges the etching liquid Econtaining the silicon solution to a drainage DR, when the whole or apart of the etching liquid E used for the etching processing isreplaced. The etching liquid drainage section 34 includes a dischargepath 34 a, a flow rate regulator 34 b, and a cooling tank 34 c.

The discharge path 34 a is connected to the circulation path 32. Theflow rate regulator 34 b is provided in the discharge path 34 a, andadjusts a discharge amount of the etching liquid E to be discharged. Theflow rate regulator 34 b is constituted by, for example, an open/closevalve, a flow rate control valve, or a flow meter.

The cooling tank 34 c temporarily stores and cools the etching liquid Eflowing through the discharge path 34 a. In the cooling tank 34 c thedischarge amount of the etching liquid E is adjusted by the flow rateregulator 34 b.

<Modifications>

Next, descriptions will be made on various modifications of thesubstrate processing system 1 according to the embodiment with referenceto FIG. 4 to FIG. 14. FIG. 4 is a schematic block diagram illustrating aconfiguration of the substrate processing system 1 according to a firstmodification of the embodiment. In the following various modifications,the same portions as those in the embodiment are denoted by the samereference numerals, and thus redundant descriptions thereof will beomitted.

As illustrated in FIG. 4, in the substrate processing system 1 accordingto the first modification, the configuration of the silicon solutionsupply 25 is different from that in the embodiment. Specifically, thesilicon solution supply path 25 b of the silicon solution supply 25 isconnected to the processing bath 31 instead of the liquid sending path22. For example, the silicon solution supply path 25 b is connected tothe outer tank 31 b of the processing bath 31.

In the first modification as well, the silicon solution may beindividually supplied to the mixture liquid M generated by the mixingdevice 10 to generate the etching liquid E.

FIG. 5 is a schematic block diagram illustrating a configuration of thesubstrate processing system 1 according to a second modification of theembodiment. As illustrated in FIG. 5, in the substrate processing system1 according to the second modification, the silicon solution supply path25 b of the silicon solution supply 25 is connected to both the liquidsending path 22 and the processing bath 31.

For example, the silicon solution supply path 25 b is connected to thejunction 22 a of the liquid sending path 22 and is also connected to theouter tank 31 b of the processing bath 31.

A flow rate regulator 25 d is provided in the silicon solution supplypath 25 b connected to the junction 22 a of the liquid sending path 22,and a flow rate regulator 25 e is provided in the silicon solutionsupply path 25 b connected to the processing bath 31.

Then, by controlling these flow rate regulators 25 d and 25 e, thesilicon solution may be individually supplied to each part of themixture liquid M generated by the mixing device 10 to generate theetching liquid E.

FIG. 6 is a schematic block diagram illustrating a configuration of thesubstrate processing system 1 according to a third modification of theembodiment. The substrate processing system 1 according to the thirdmodification is provided with a function for always maintaining thesilicon concentration of the etching liquid E within the processing bath31 at a constant level or less when silicon is eluted into the etchingliquid E from the wafer W after the etching processing on the wafer W isstarted in the processing bath 31.

Then, in order to provide such a function, a part of the configurationis different from that of the above described first modification. Aspecific difference in the configuration will be described below.

As illustrated in FIG. 6, in the third modification, a back pressurevalve 51 is provided on the downstream side of the diverging portion 15c in the circulation path 15. The back pressure valve 51 adjusts thepressure in the circulation path 15 on the upstream side of the backpressure valve 51 (for example, the diverging portion 15 c).

A thermometer 52 is provided on the upstream side of a diverging portion22 b in the liquid sending path 22. Such a thermometer 52 measures thetemperature of the mixture liquid M flowing through the liquid sendingpath 22. The diverging portion 22 b is a portion in the liquid sendingpath 22, from which a liquid sending path 22 c connected to the innertank 31 a and a liquid sending path 22 d connected to the outer tank 31b diverge. That is, the liquid sending path 22 c and the liquid sendingpath 22 d are a part of the liquid sending path 22.

A valve 53 is provided in the liquid sending path 22 c, and the liquidsending path 22 d is provided with a valve 54, a flow meter 55, aconstant pressure valve 56, a throttle valve 57, a diverging portion 22e, and a valve 58 in order from the upstream side. From the divergingportion 22 e, a return path 24 that returns the mixture liquid M to thetank 14 diverges. Such a return path 24 has a valve 59.

The silicon solution supply path 25 b of the silicon solution supply 25is connected to the inner tank 31 a of the processing bath 31.

The controller alternately opens/closes the valve 53 and the valve 54.Accordingly, the controller may send the mixture liquid M whileswitching between the inner tank 31 a and the outer tank 31 b.

The flow meter 55 measures the flow rate of the mixture liquid M flowingthrough the liquid sending path 22 d. Here, in the third modification,the flow meter 55 may correct the flow rate of the mixture liquid Mbased on the temperature of the mixture liquid M measured by thethermometer 52. For example, the controller may correct the flow rateinformation of the mixture liquid M obtained from the flow meter 55based on the temperature information of the mixture liquid M obtainedfrom the thermometer 52.

Accordingly, in the third modification, even when the temperature of themixture liquid M is significantly changed in a range from a roomtemperature to a high temperature, it is possible to accurately measurethe flow rate of the mixture liquid M flowing through the flow meter 55.

The constant pressure valve 56 adjusts the pressure in the liquidsending path 22 d on the downstream side of the constant pressure valve56. The throttle valve 57 adjusts the flow rate of the mixture liquid Mflowing through the liquid sending path 22 d.

The controller alternately opens/closes the valve 58 and the valve 59.Accordingly, the controller may send the mixture liquid M whileswitching between the outer tank 31 b and the tank 14.

Next, a method of adjusting the silicon concentration in the mixtureliquid M in the third modification will be described with reference toFIG. 7 and FIG. 8. FIG. 7 is a timing chart illustrating a specificexample of a behavior pattern of each unit in the substrate processingsystem 1, during various processes when the mixture liquid M isinitially sent to the processing bath 31 according to the thirdmodification of the embodiment.

As illustrated in FIG. 7, in the third modification, a mixing process, aheating process, a filtration process, and a liquid sending process aresequentially performed. First, the controller starts the mixing processby operating (turning ON) the phosphoric acid aqueous solution supply 11from time T20, and supplying the phosphoric acid aqueous solution to thetank 14.

At this point in time T20, the precipitation inhibitor supply 12, thesilicon solution supply 25, the pump 16, and the heater 17 are notoperating (OFF state). At the point in time T20, since the open/closevalve 18 is in a close state and the open/close valve 21 is in an openstate, in this state, the filter 19 is bypassed by the bypass flow path20 (a filter bypass is in an ON state), and the back pressure valve 51is in a fully open state.

At point in time T20, the flow rate regulator 23 is in a close state(OFF state), and OFF signals are output from the first liquid levelsensor S1 and the second liquid level sensor S2 since nothing is storedin the tank 14.

Then, at time T21 when the phosphoric acid aqueous solution has beensupplied in a predetermined amount to the tank 14, the controller formsa circulating flow in the circulation path 15 by operating (turning ON)the pump 16.

Next, the liquid level of the phosphoric acid aqueous solution stored inthe tank 14 gradually rises. When the liquid level becomes equal to orhigher than the predetermined second height at time T22, an ON signal isoutput from the second liquid level sensor S2. Then, the controllersupplies the precipitation inhibitor to the tank 14 by operating(turning ON) the precipitation inhibitor supply 12 from time T22, andstops (turns OFF) the phosphoric acid aqueous solution supply 11.

Next, at time T23 when the precipitation inhibitor has been supplied ina predetermined amount to the tank 14, the controller stops (turns OFF)the precipitation inhibitor supply 12, and supplies the phosphoric acidaqueous solution to the tank 14 by operating (turning ON) the phosphoricacid aqueous solution supply 11.

Next, at time T24, when the liquid level of the mixture liquid M becomesequal to or higher than the predetermined first height, an ON signal isoutput from the first liquid level sensor S1. Then, the controllerconsiders that the phosphoric acid aqueous solution has been supplied ina predetermined amount to the tank 14, and stops (turns OFF) thephosphoric acid aqueous solution supply 11 at time T24. Accordingly, themixing process is completed.

As described above, in the third modification, the controller operatesthe pump 16 before the precipitation inhibitor is supplied to the tank14. Accordingly, the circulating flow may be formed in the circulationpath 15 before the precipitation inhibitor is supplied, and thus, it ispossible to improve a mixing property between the phosphoric acidaqueous solution and the precipitation inhibitor.

In the third modification, the controller does not simultaneously supplythe phosphoric acid aqueous solution and the precipitation inhibitor tothe tank 14, but individually supplies each to the tank 14. Accordingly,it is possible to suppress the output of an ON signal from the firstliquid level sensor S1 before the precipitation inhibitor is supplied ina predetermined amount. Therefore, according to the third modification,it is possible to reliably supply the precipitation inhibitor in apredetermined amount to the tank 14.

Next, the controller starts the heating process by operating (turningON) the heater 17 from time T24, and heating the mixture liquid Mcirculating in the circulation path 15. The controller heats the mixtureliquid M by the heater 17, thereby heating the mixture liquid M storedin the tank 14.

Next, at time T25 when the mixture liquid M within the tank 14 is heatedto a predetermined temperature (for example, less than 100° C.), theheating process is completed.

Next, the controller starts the filtration process by turning OFF thefilter bypass from time T25. That is, from time T25, the controllerchanges the open/close valve 18 to an open state and changes theopen/close valve 21 to a close state so as to form a circulating flowflowing through the filter 19, in the circulation path 15. Accordingly,contaminants such as particles contained in the mixture liquid M areremoved.

Then, the filtration process is completed at time T26 when thecontaminants such as particles contained in the mixture liquid M aresufficiently removed.

Next, the controller starts the liquid sending process from time T26.Specifically, the controller places (turns ON) the flow rate regulator23 in an open state from time T26. Although not illustrated in FIG. 7,the controller changes the valve 53 to an open state and changes thevalve 54 to a close state.

Accordingly, the controller sends the mixture liquid M from the mixingdevice 10 to the inner tank 31 a of the substrate processor 30 throughthe circulation path 15, the liquid sending path 22, and the liquidsending path 22 c.

Then, the mixture liquid M within the tank 14 is reduced, and the liquidlevel becomes lower than the predetermined first height at time T27.Accordingly, an OFF signal is output from the first liquid level sensor51.

The controller stops (turns OFF) the heater 17 at the same timing (timeT26) as the liquid sending start of the mixture liquid M. Accordingly,it is possible to suppress the temperature of the mixture liquid M frombecoming higher than the predetermined temperature (for example, lessthan 100° C.).

Next, at time T28 when the mixture liquid M has been supplied in apredetermined amount to the processing bath 31, the controller operates(turns ON) the silicon solution supply 25, and places (turns OFF) theflow rate regulator 23 in a close state. Accordingly, the controllersends the silicon solution to the inner tank 31 a of the substrateprocessor 30 through the silicon solution supply path 25 b.

The controller stops (turns OFF) the pump 16 at the same timing (timeT28) as the supply start of the silicon solution. Then, at time T29 whenthe silicon solution has been sent in a predetermined amount, the liquidsending process is completed.

Through the processes described so far, the controller may store theetching liquid E having a desired silicon concentration, in theprocessing bath 31 when initially sending the mixture liquid M to theprocessing bath 31. Therefore, according to the third modification, fromthe point in time when an etching processing on the wafer W is started,it is possible to improve the etching selectivity of the silicon nitridefilm to the silicon oxide film.

In the third modification, the controller supplies both the mixtureliquid M and the silicon solution to the inner tank 31 a of theprocessing bath 31. Accordingly, in the third modification, the mixtureliquid M and the silicon solution may be mixed while overflowing fromthe inner tank 31 a to the outer tank 31 b. Thus, it is possible toimprove the mixing property between the mixture liquid M and the siliconsolution.

FIG. 8 is a timing chart illustrating a specific example of a behaviorpattern of each unit in the substrate processing system 1, duringvarious processes when the silicon concentration of the etching liquid Eis adjusted in the processing bath 31 according to the thirdmodification of the embodiment.

In FIG. 8, descriptions will be made on a mixing process to a liquidsending process of the mixture liquid M to be sent when silicon iseluted into the etching liquid E from the wafer W after the etchingprocessing on the wafer W is started in the processing bath 31.

First, the controller starts the mixing process by operating (turningON) the phosphoric acid aqueous solution supply 11 from time T30, andsupplying the phosphoric acid aqueous solution to the tank 14.

At this point in time T30, the precipitation inhibitor supply 12, thesilicon solution supply 25, the pump 16, and the heater 17 are notoperating (OFF state). At the point in time T30, since the open/closevalve 18 is in a close state and the open/close valve 21 is in an openstate, in this state, the filter 19 is bypassed by the bypass flow path20 (the filter bypass is in an ON state), and the back pressure valve 51is in a fully open state.

At point in time T30, the flow rate regulator 23 is in a close state(OFF state), and OFF signals are output from the first liquid levelsensor S1 and the second liquid level sensor S2 since nothing is storedin the tank 14.

Then, at time T31 when the phosphoric acid aqueous solution has beensupplied in a predetermined amount to the tank 14, the controller formsa circulating flow in the circulation path 15 by operating (turning ON)the pump 16.

Next, the liquid level of the phosphoric acid aqueous solution stored inthe tank 14 gradually rises. When the liquid level becomes equal to orhigher than the predetermined second height at time T32, an ON signal isoutput from the second liquid level sensor S2. Then, the controllersupplies the precipitation inhibitor to the tank 14 by operating(turning ON) the precipitation inhibitor supply 12 from time T32, andstops (turns OFF) the phosphoric acid aqueous solution supply 11.

Next, at time T33 when the precipitation inhibitor has been supplied ina predetermined amount to the tank 14, the controller stops (turns OFF)the precipitation inhibitor supply 12, and supplies the phosphoric acidaqueous solution to the tank 14 by operating (turning ON) the phosphoricacid aqueous solution supply 11.

Next, at time T34, when the liquid level of the mixture liquid M becomesequal to or higher than the predetermined first height, an ON signal isoutput from the first liquid level sensor S1. Then, the controllerconsiders that the phosphoric acid aqueous solution has been supplied ina predetermined amount to the tank 14, and stops (turns OFF) thephosphoric acid aqueous solution supply 11 at time T34. Accordingly, themixing process is completed.

Next, the controller starts the liquid sending process from time T34.Specifically, at time T34, the controller places (turns ON) the flowrate regulator 23 in an open state and places the back pressure valve 51in a throttled state. Although not illustrated in FIG. 8, the controllerchanges the valve 53 to a close state, and changes the valve 54 to anopen state.

Accordingly, the controller sends the mixture liquid M from the mixingdevice 10 to the outer tank 31 b of the substrate processor 30 throughthe circulation path 15, the liquid sending path 22, and the liquidsending path 22 d. Then, the mixture liquid M within the tank 14 isreduced, and the liquid level becomes lower than the predetermined firstheight at time T35. Accordingly, an OFF signal is output from the firstliquid level sensor S1.

Here, in the third modification, the controller performs a control ofalways maintaining the silicon concentration within the processing bath31 at a constant level or less, based on the silicon concentration ofthe etching liquid E within the processing bath 31, which is obtainedfrom the silicon concentration sensor 42.

For example, when the silicon concentration of the etching liquid Ewithin the processing bath 31 becomes higher than a given threshold, thecontroller discharges the etching liquid E having a high siliconconcentration by placing the flow rate regulator 34 b in an open state,and supplies the mixture liquid M in the same amount as the dischargedetching liquid E.

Here, in third modification, since the mixing process of the mixtureliquid M is completed by the mixing device 10, the mixture liquid M notcontaining the silicon solution may be supplied to the processing bath31 when necessary.

Accordingly, the controller may keep the amount of the etching liquid Estored within the processing bath 31 constant and reduce the siliconconcentration of the etching liquid E within the processing bath 31.Therefore, according to the third modification, it is possible to alwaysmaintain the silicon concentration within the processing bath 31 at aconstant level or less.

In the third modification, when the supply of the mixture liquid M inthe processing bath 31 is unnecessary, the controller may return themixture liquid M flowing through the liquid sending path 22 d from thereturn path 24 to the tank 14.

That is, when the supply of the mixture liquid M in the processing bath31 is unnecessary, the controller may change the valve 58 to a closestate and change the valve 59 to an open state, so that the mixtureliquid M may be circulated by using the circulation path 15, the liquidsending path 22, the liquid sending path 22 d, and the return path 24.

Accordingly, a state where the mixture liquid M is discharged from theliquid sending path 22 d to the outer tank 31 b (that is, a state wherethe supply of the mixture liquid M is necessary) may be aligned with astate where the mixture liquid M is not discharged from the liquidsending path 22 d to the outer tank 31 b (that is, a state where thesupply of the mixture liquid M is unnecessary).

Accordingly, according to the third modification, since the mixtureliquid M may be more accurately discharged, it is possible to moreaccurately perform a processing of always maintaining the siliconconcentration within the processing bath 31 at a constant level or less.

In the third modification, during the liquid sending process of themixture liquid M, the controller may place the back pressure valve 51 ina throttled state. Accordingly, the controller may increase the pressureof the diverging portion 15 c in the circulation path 15, and thus, itis possible to secure the pressure required to return the mixture liquidM from the diverging portion 15 c to the tank 14 through the liquidsending path 22, the liquid sending path 22 d, and the return path 24.

In the third modification, when the flow rate of the mixture liquid Mdischarged from the liquid sending path 22 d to the outer tank 31 b isadjusted, the flow rate is roughly adjusted by using the throttle valve57, and the flow rate is finely adjusted by using the flow meter 55 andthe constant pressure valve 56.

Here, in the third modification, the pressure of the mixture liquid Mwithin the flow meter 55 may be feedback-controlled by the constantpressure valve 56 so that the flow rate of the mixture liquid M withinthe flow meter 55 may be kept constant. Accordingly, since the mixtureliquid M may be discharged in a more accurate amount, it is possible tomore accurately perform a processing of always maintaining the siliconconcentration within the processing bath 31 at a constant level or less.

In the third modification, when adjusting the silicon concentration ofthe etching liquid E, the controller may supply the mixture liquid M tothe outer tank 31 b instead of the inner tank 31 a. Accordingly, ascompared to that in the case where the mixture liquid M is directlysupplied to the inner tank 31 a where the wafer W is being processed,the silicon concentration of the etching liquid E in the inner tank 31 amay be suppressed from being rapidly changed.

Therefore, according to the third modification, it is possible to stablyperform the etching processing of the wafer W.

In the third modification, when the silicon concentration of the etchingliquid E is adjusted, the mixture liquid M at room temperature may besupplied to the processing bath 31. Accordingly, since the heatingprocess may be omitted, the time until the liquid sending process of themixture liquid M may be shortened. Therefore, according to the thirdmodification, it is possible to quickly perform the adjustmentprocessing of the silicon concentration.

When the silicon concentration of the etching liquid E is adjusted, themixture liquid M is supplied to the outer tank 31 b and then is heatedby the heater 40 until reaching the inner tank 31 a. Thus, there is noparticular problem even if the heating process is omitted duringgeneration of the mixture liquid M.

In the third modification, when the silicon concentration of the etchingliquid E is adjusted, the filtration process of the mixture liquid M maybe omitted. Accordingly, since the time until the liquid sending processof the mixture liquid M may be shortened, it is possible to quicklyperform the adjustment processing of the silicon concentration.

When the silicon concentration of the etching liquid E is adjusted, themixture liquid M is supplied to the outer tank 31 b, and then isfiltered through the filter 41 until reaching the inner tank 31 a. Thus,there is no particular problem even if the filtration process is omittedduring generation of the mixture liquid M.

FIG. 9 is a schematic block diagram illustrating a configuration of thesubstrate processing system 1 according to a fourth modification of theembodiment. In the following modifications, descriptions will be made ona case where three processing baths 31A to 31C are provided in thesubstrate processing system 1.

In the substrate processing system 1 according to the fourthmodification, three cabinets 101 to 103 are provided. The cabinet 101accommodates an etching liquid supply 2A constituted by a mixing device10A and a silicon solution supply 25A. Then, for example, the mixtureliquid M (see FIG. 1) is supplied from such an etching liquid supply 2Ato the processing bath 31A through a liquid sending path 22A.

The cabinet 102 accommodates an etching liquid supply 2B constituted bya mixing device 10B and a silicon solution supply 25B. Then, the mixtureliquid M and the silicon solution are supplied from such an etchingliquid supply 2B to the processing bath 31B through a liquid sendingpath 22B.

The cabinet 103 accommodates an etching liquid supply 2C constituted bya mixing device 10C and a silicon solution supply 25C. Then, the mixtureliquid M and the silicon solution are supplied from such an etchingliquid supply 2C to the processing bath 31C through a liquid sendingpath 22C.

In the following description, the etching liquid supplies 2A to 2C mayalso be collectively referred to as “the etching liquid supply 2,” themixing devices 10A to 10C may also be collectively referred to as “themixing device 10,” and the processing baths 31A to 31C may also becollectively referred to as “the processing bath 31.”

FIG. 10 is a view illustrating a specific example of the processing flowof the etching liquid supplies 2A to 2C according to the fourthmodification of the embodiment. As illustrated in FIG. 10, when a liquidexchange process of the etching liquid E (hereinafter, also referred toas a “liquid exchange stage”) is performed in each of the processingbaths 31A to 31C, first, the etching liquid supply 2A generates themixture liquid M by the mixing device 10A.

Next, the etching liquid supply 2A supplies the mixture liquid M fromthe mixing device 10A and the silicon solution from the silicon solutionsupply 25A to the processing bath 31A through the liquid sending path22A, and performs the liquid exchange process in the processing bath31A.

Likewise, in the liquid exchange stage, first, the etching liquid supply2B generates the mixture liquid M by the mixing device 10B.Subsequently, the etching liquid supply 2B supplies the mixture liquid Mfrom the mixing device 10B, and the silicon solution from the siliconsolution supply 25B to the processing bath 31B through the liquidsending path 22B, and performs the liquid exchange process in theprocessing bath 31B.

Likewise, in the liquid exchange stage, first, the etching liquid supply2C generates the mixture liquid M by the mixing device 10C.Subsequently, the etching liquid supply 2C supplies the mixture liquid Mfrom the mixing device 10C, and the silicon solution from the siliconsolution supply 25C to the processing bath 31C through the liquidsending path 22C, and performs the liquid exchange process in theprocessing bath 31C.

That is, in the liquid exchange stage where the wafer W is not immersedin the processing bath 31, the etching liquid supply 2 supplies themixture liquid M and the silicon solution to the processing bath 31.

As illustrated in FIG. 10, subsequently to the liquid exchange stage, ineach of the processing baths 31A to 31C, a first process (hereinafter,also referred to as a “first process step”) of the wafer W is performed.In such a first process step, since the wafer W is immersed in theprocessing bath 31A, silicon is eluted from the wafer W.

Therefore, in order to adjust the silicon concentration of theprocessing bath 31A, the etching liquid supply 2A generates the mixtureliquid M by the mixing device 10A while supplying the generated mixtureliquid M to the processing bath 31A. The substrate processing system 1performs a concentration adjustment processing of the processing bath31A by discharging the mixture liquid M containing the silicon solutionfrom the processing bath 31A through the etching liquid drainage section34 (see FIG. 1).

That is, in the first process step where the wafer W is immersed in theprocessing bath 31, the mixture liquid M not containing the siliconsolution is supplied to the processing bath 31, and the mixture liquid Mcontaining the silicon solution (that is, the etching liquid E) isdischarged from the processing bath 31.

Likewise, in the first process step, the etching liquid supply 2Bgenerates the mixture liquid M by the mixing device 10B while supplyingthe generated mixture liquid M to the processing bath 31B. The substrateprocessing system 1 performs a concentration adjustment processing ofthe processing bath 31B by discharging the mixture liquid M containingthe silicon solution from the processing bath 31B through the etchingliquid drainage section 34.

Likewise, in the first process step, the etching liquid supply 2Cgenerates the mixture liquid M by the mixing device 10C while supplyingthe generated mixture liquid M to the processing bath 31C. The substrateprocessing system 1 performs a concentration adjustment processing ofthe processing bath 31C by discharging the mixture liquid M containingthe silicon solution from the processing bath 31C through the etchingliquid drainage section 34.

Then, in a second process of the wafer W to be performed subsequently tothe first process step (hereinafter, also referred to as a “secondprocess step”) as well, in the etching liquid supplies 2A to 2C, thesame processing as that in the first process step is performed.

As described above, in the fourth modification, one etching liquidsupply 2 is connected to one processing bath 31. Accordingly, there isno need to provide a plurality of etching liquid supplies 2 to eachprocessing bath 31. Thus, the substrate processing system 1 may beconfigured at a low cost.

In the fourth modification, the mixture liquid M is generated by themixing device 10 while the generated mixture liquid M is supplied to theprocessing bath 31. That is, when the discharge amount of the mixtureliquid M discharged from the processing bath 31 for the purpose of theconcentration adjustment is equal to the generation amount of themixture liquid M that may be generated by the mixing device 10, theprocessing flow illustrated in FIG. 10 may be performed.

FIG. 11 is a schematic block diagram illustrating a configuration of thesubstrate processing system 1 according to a fifth modification of theembodiment. In the substrate processing system 1 according to the fifthmodification, three cabinets 101 to 103 are provided.

The cabinet 101 accommodates an etching liquid supply 2A constituted bya mixing device 10A and a silicon solution supply 25A, and an etchingliquid supply 2B constituted by a mixing device 10B and a siliconsolution supply 25B.

Then, for example, the mixture liquid M (see FIG. 1) is supplied fromthe etching liquid supply 2A to a processing bath 31A through a liquidsending path 22A, and the mixture liquid M and the silicon solution aresupplied from the etching liquid supply 2B to the processing bath 31Athrough a liquid sending path 22B.

The cabinet 102 accommodates an etching liquid supply 2C constituted bya mixing device 10C and a silicon solution supply 25C, and an etchingliquid supply 2D constituted by a mixing device 10D and a siliconsolution supply 25D.

Then, the mixture liquid M and the silicon solution are supplied fromthe etching liquid supply 2C to a processing bath 31B through a liquidsending path 22C, and the mixture liquid M and the silicon solution aresupplied from the etching liquid supply 2D to the processing bath 31Bthrough a liquid sending path 22D.

The cabinet 103 accommodates an etching liquid supply 2E constituted bya mixing device 10E and a silicon solution supply 25E, and an etchingliquid supply 2F constituted by a mixing device 10F and a siliconsolution supply 25F.

Then, the mixture liquid M and the silicon solution are supplied fromthe etching liquid supply 2E to a processing bath 31C through a liquidsending path 22E, and the mixture liquid M and the silicon solution aresupplied from the etching liquid supply 2F to the processing bath 31Cthrough a liquid sending path 22F.

FIG. 12 is a view illustrating a specific example of the processing flowof the etching liquid supplies 2A to 2F according to the fifthmodification of the embodiment. As illustrated in FIG. 12, in a liquidexchange stage, first, the etching liquid supply 2A generates themixture liquid M by the mixing device 10A.

Next, the etching liquid supply 2A supplies the mixture liquid M fromthe mixing device 10A, and the silicon solution from the siliconsolution supply 25A to the processing bath 31A through the liquidsending path 22A, and performs the liquid exchange process in theprocessing bath 31A.

In parallel with the liquid exchange process by the etching liquidsupply 2A, the etching liquid supply 2B generates the mixture liquid Mby the mixing device 10B.

Then, in a first process step to be performed subsequently to the liquidexchange stage, the etching liquid supply 2B supplies the mixture liquidM generated by the mixing device 10B to the processing bath 31A. Thesubstrate processing system 1 performs a concentration adjustmentprocessing of the processing bath 31A by discharging the mixture liquidM containing the silicon solution from the processing bath 31A throughthe etching liquid drainage section 34.

In parallel with the concentration adjustment processing by the etchingliquid supply 2B, the etching liquid supply 2A generates the mixtureliquid M by the mixing device 10A.

In the fifth modification, a mixture liquid generation time in themixing device 10 is shorter than a processing time required for oneetching processing. Therefore, in the fifth modification, after themixture liquid M is generated in a predetermined amount, the etchingliquid supply 2A waits until the following second process step.

Then, in a second process step to be performed subsequently to the firstprocess step, the etching liquid supply 2A supplies the mixture liquid Mgenerated by the mixing device 10A to the processing bath 31A. Thesubstrate processing system 1 performs a concentration adjustmentprocessing of the processing bath 31A by discharging the mixture liquidM containing the silicon solution from the processing bath 31A throughthe etching liquid drainage section 34.

In parallel with the concentration adjustment processing by the etchingliquid supply 2A, the etching liquid supply 2B generates the mixtureliquid M by the mixing device 10B. Then, after the mixture liquid M isgenerated in a predetermined amount, the etching liquid supply 2B waitsuntil the following third process step.

As illustrated in FIG. 12, the same processes as the above describedprocesses in the etching liquid supplies 2A and 2B are performed in theetching liquid supplies 2C and 2D, and the etching liquid supplies 2Eand 2F.

As described above, in the fifth modification, two etching liquidsupplies 2 are connected to one processing bath 31, and for eachprocess, the mixture liquid M is exclusively supplied from the twoetching liquid supplies 2.

Accordingly, the mixture liquid M that is accurately produced with adesired concentration or temperature may be supplied to the processingbath 31. Therefore, according to the fifth modification, it is possibleto perform a highly accurate etching processing.

FIG. 13 is a schematic block diagram illustrating a configuration of thesubstrate processing system 1 according to a sixth modification of theembodiment. In the substrate processing system 1 according to the sixthmodification, five cabinets 101 to 105 are provided.

In the substrate processing system 1 according to the sixthmodification, the configuration of the cabinets 101 to 103 is the sameas that in the above described fifth modification, and thus, detaileddescriptions thereof will be omitted.

The cabinet 104 accommodates an etching liquid supply 2G constituted bya mixing device 10G and a silicon solution supply 25G, and an etchingliquid supply 2H constituted by a mixing device 10H and a siliconsolution supply 25H.

Then, the mixture liquid M and the silicon solution are supplied fromthe etching liquid supply 2G to the processing bath 31A through a liquidsending path 22G, and the mixture liquid M and the silicon solution aresupplied from the etching liquid supply 2H to the processing bath 31Bthrough a liquid sending path 22H.

The cabinet 105 accommodates an etching liquid supply 2I constituted bya mixing device 10I and a silicon solution supply 25I. Then, the mixtureliquid M and the silicon solution are supplied from the etching liquidsupply 2I to the processing bath 31C through a liquid sending path 22I.

FIG. 14 is a view illustrating a specific example of the processing flowof the etching liquid supplies 2A to 2I according to the sixthmodification of the embodiment. As illustrated in FIG. 14, in a firstprocess step, the etching liquid supply 2A supplies the mixture liquid Mgenerated by the mixing device 10A to the processing bath 31A.

The substrate processing system 1 performs a concentration adjustmentprocessing of the processing bath 31A by discharging the mixture liquidM containing the silicon solution from the processing bath 31A throughthe etching liquid drainage section 34.

In parallel with the concentration adjustment processing by the etchingliquid supply 2A, the etching liquid supply 2B generates the mixtureliquid M by the mixing device 10B, and the etching liquid supply 2Ggenerates the mixture liquid M by the mixing device 10G.

In the sixth modification, a mixture liquid generation time in themixing device 10 is longer than a processing time required for oneetching processing. Therefore, in a second process step to be performedsubsequently to the first process step, a mixture liquid generationprocessing by the etching liquid supply 2B is not completed in time.

Therefore, in the sixth modification, the mixture liquid M is suppliedto the processing bath 31A from the etching liquid supply 2G in whichgeneration of the mixture liquid M is completed at a timing for the timefor the second process step.

The substrate processing system 1 performs the concentration adjustmentprocessing of the processing bath 31A by discharging the mixture liquidM containing the silicon solution from the processing bath 31A throughthe etching liquid drainage section 34.

In parallel with the concentration adjustment processing by the etchingliquid supply 2G, the etching liquid supply 2B continues to generate themixture liquid M by the mixing device 10B, and the etching liquid supply2A generates the mixture liquid M by the mixing device 10A. After themixture liquid M is generated in a predetermined amount, the etchingliquid supply 2B waits until the following third process step.

Then, in the third process step to be performed subsequently to thesecond process step, the mixture liquid M is supplied to the processingbath 31A from the etching liquid supply 2B in which generation of themixture liquid M is completed.

The substrate processing system 1 performs the concentration adjustmentprocessing of the processing bath 31A by discharging the mixture liquidM containing the silicon solution from the processing bath 31A throughthe etching liquid drainage section 34.

In parallel with the concentration adjustment processing by the etchingliquid supply 2B, the etching liquid supply 2A continues to generate themixture liquid M by the mixing device 10A, and the etching liquid supply2G generates the mixture liquid M by the mixing device 10G. After themixture liquid M is generated in a predetermined amount, the etchingliquid supply 2A waits until the following fourth process step.

As illustrated in FIG. 14, the same processes as the above describedprocesses in the etching liquid supplies 2A, 2B, and 2G are performed inthe etching liquid supplies 2C, 2D, and 2H, and the etching liquidsupplies 2E, 2F, and 2I.

As described above, in the sixth modification, three etching liquidsupplies 2 are connected to one processing bath 31, and the mixtureliquid M is supplied from the three etching liquid supplies 2 in theorder in which the mixture liquid M is generated.

Accordingly, even when a mixture liquid generation time in the mixingdevice 10 is longer than a processing time required for one etchingprocessing, the mixture liquid M that is accurately produced with adesired concentration or temperature may be supplied to the processingbath 31.

Therefore, according to the sixth modification, even when a mixtureliquid generation time in the mixing device 10 is longer than aprocessing time required for one etching processing, a highly accurateetching processing may be performed.

In the fifth modification and the sixth modification, descriptions havebeen made on an example in which the silicon solution supplies 25A to25I are individually connected to the liquid sending paths 22A to 22I,respectively. Meanwhile, the present disclosure is not limited to a casewhere each silicon solution supply 25 is connected to each of the liquidsending paths 22A to 22I. Each silicon solution supply 25 may beprovided for each of the processing baths 31A to 31C.

In the fifth modification and the sixth modification, descriptions havebeen made on an example in which three processing baths 31A to 31C areprovided in the substrate processing system 1, but the number of theprocessing baths 31 provided in the substrate processing system 1 is notlimited to three.

The substrate processing apparatus according to the embodiment (thesubstrate processing system 1) includes the processing bath 31, themixing device 10, the liquid sending path 22, and the silicon solutionsupply 25. The processing bath 31 processes the substrate (the wafer W)through immersion. The mixing device 10 generates a mixture liquid M bymixing a phosphoric acid aqueous solution with an additive thatsuppresses precipitation of silicon oxide. The liquid sending path 22sends the mixture liquid M from the mixing device 10 to the processingbath 31. The silicon solution supply 25 is connected to at least one ofthe liquid sending path 22 and the processing bath 31, and supplies asilicon-containing compound aqueous solution (a silicon solution) to themixture liquid M supplied from the mixing device 10. Accordingly, it ispossible to properly perform an etching processing by an etching liquidE containing a phosphoric acid aqueous solution and a silicon solution.

In the substrate processing apparatus according to the embodiment (thesubstrate processing system 1), the mixing device 10 includes the tank14, and the circulation path 15 that exits from the tank 14 and returnsto the tank 14, and the liquid sending path 22 is provided divergingfrom the circulation path 15. Accordingly, since there is no need toprovide a separate pump in the liquid sending path 22 for the purpose ofthe liquid sending process of the mixture liquid M, it is possible tosend the mixture liquid M at a low cost.

In the substrate processing apparatus according to the embodiment (thesubstrate processing system 1), the circulation path 15 includes thefilter 19 that filters the mixture liquid M, and the bypass flow path 20that bypasses the filter 19. Accordingly, since in the circulation path15, a pressure loss occurring in the filter 19 may be reduced, it ispossible to efficiently circulate the mixture liquid M stored in thetank 14.

The substrate processing apparatus according to the embodiment (thesubstrate processing system 1) further includes the back pressure valve51 provided in the circulation path 15 on the downstream side of thediverging portion 15 c from which the liquid sending path 22 diverges.Accordingly, it is possible to secure the pressure required to returnthe mixture liquid M from the diverging portion 15 c to the tank 14through the liquid sending path 22, the liquid sending path 22 d, andthe return path 24.

The substrate processing apparatus according to the embodiment (thesubstrate processing system 1) further includes the flow meter 55 andthe thermometer 52 provided in the liquid sending path 22. The flowmeter 55 corrects the flow rate of the mixture liquid M based on thetemperature of the mixture liquid M measured by the thermometer 52.Accordingly, even when the temperature of the mixture liquid M issignificantly changed in a range from a room temperature to a hightemperature, it is possible to accurately evaluate the flow rate of themixture liquid M flowing through the flow meter 55.

The substrate processing apparatus according to the embodiment (thesubstrate processing system 1) further includes the return path 24 thatdiverges from the downstream side of the flow meter 55 in the liquidsending path 22, and returns to the tank 14. Accordingly, it is possibleto more accurately perform a processing of always maintaining thesilicon concentration within the processing bath 31 at a constant levelor less.

The substrate processing apparatus according to the embodiment (thesubstrate processing system 1) further includes the controller thatcontrols the processing bath 31, the mixing device 10, the liquidsending path 22, and the silicon solution supply 25. The controllerfully opens the back pressure valve 51 when the mixture liquid M isgenerated while circulating the mixture liquid M through the circulationpath 15, and throttles the back pressure valve 51 when the mixtureliquid M is sent to the liquid sending path 22. Accordingly, it ispossible to secure the pressure required to return the mixture liquid Mfrom the diverging portion 15 c to the tank 14 through the liquidsending path 22, the liquid sending path 22 d, and the return path 24.

The substrate processing apparatus according to the embodiment (thesubstrate processing system 1) further includes the controller thatcontrols the processing bath 31, the mixing device 10, the liquidsending path 22, and the silicon solution supply 25. The mixing device10 includes the heater 17 that heats the mixture liquid M, and thecontroller controls the heater 17 so as to set the temperature of themixture liquid M based on whether to supply the silicon-containingcompound aqueous solution (the silicon solution) to the mixture liquidM. Accordingly, when the silicon solution is supplied to the mixtureliquid M, it is possible to suppress the silicon solution containingmoisture from being exposed to a high temperature and being bumped. Whenthe silicon solution is not supplied to the mixture liquid M, it ispossible to suppress the temperature of the etching liquid E during theprocessing from being reduced due to the supply of the mixture liquid M.

In the substrate processing apparatus according to the embodiment (thesubstrate processing system 1), a plurality of mixing devices 10 isprovided for one processing bath 31, and each of the mixing devices 10exclusively supplies the mixture liquid M to one processing bath 31.Accordingly, the mixture liquid M that is accurately produced with adesired concentration or temperature may be supplied to the processingbath 31.

In the substrate processing apparatus according to the embodiment (thesubstrate processing system 1), a plurality of mixing devices 10 isprovided for a plurality of processing baths 31, and the mixture liquidM is supplied to the processing bath 31 that requires the supply of themixture liquid M from the mixing device 10 in which generation of themixture liquid M is completed, in order. Accordingly, even when amixture liquid generation time in the mixing device 10 is longer than aprocessing time required for one etching processing, the mixture liquidM that is accurately produced with a desired concentration ortemperature may be supplied to the processing bath 31.

<Details of Mixing Process and Substrate Processing>

Next, details of a mixing process and a substrate processing executed bythe substrate processing system 1 according to the embodiment and thethird modification will be described with reference to FIG. 15 and FIG.16. FIG. 15 is a flow chart illustrating a processing procedure of amixing process and a substrate processing according to the embodiment.

First, the controller determines whether a wafer W is immersed in theprocessing bath 31 (step S101). Then, when the wafer W is not immersedin the processing bath 31 (step S101, No), for example, when a liquidexchange process is performed in the processing bath 31, the controllerperforms a mixture liquid generation processing of generating a mixtureliquid M by the mixing device 10 (step S102).

Next, the controller controls the heater 17 so as to perform a heatingprocessing of heating the generated mixture liquid M (step S103). Inthis step S103, the controller heats the mixture liquid M to, forexample, a predetermined temperature of less than 100° C.

Next, the controller controls the silicon solution supply 25 so as toperform a silicon solution supply processing of supplying a siliconsolution to the processing bath 31 (step S104). Then, the controllercontrols the mixing device 10 and the liquid sending path 22 so as toperform a mixture liquid sending processing of sending the mixtureliquid M to the processing bath 31 (step S105).

The order of the silicon solution supply processing in step S104 and themixture liquid sending processing in step S105 may be reversed or theprocessings may be performed in parallel.

Next, the controller controls the substrate processor 30 so as toperform a heating processing of heating the mixture liquid M to whichthe silicon solution has been supplied (step S106). In this step S106,the controller heats the mixture liquid M to which the silicon solutionhas been supplied to, for example, a temperature of about 165° C.

Finally, the controller controls the substrate processor 30 so as toperform an immersion processing of immersing the wafer W in the mixtureliquid M to which the silicon solution has been supplied (step S107),and completes the process.

Meanwhile, when the wafer W is immersed in the processing bath 31 (stepS101, Yes), for example, when the wafer W is etched in the processingbath 31, the controller performs a mixture liquid generation processingof generating the mixture liquid M by the mixing device 10 (step S108).

Next, the controller controls the heater 17 so as to perform a heatingprocessing of heating the generated mixture liquid M (step S109). Inthis step S109, the controller heats the mixture liquid M to, forexample, a temperature of about 165° C.

Next, the controller controls the mixing device 10 and the liquidsending path 22 so as to perform a mixture liquid sending processing ofsending the mixture liquid M to the processing bath 31 (step S110). Inparallel with this mixture liquid sending processing, the controllerperforms a mixture liquid discharge processing of discharging themixture liquid M containing the silicon solution from the processingbath 31 (step S111).

Accordingly, when silicon is eluted from a silicon nitride film withinthe wafer W and the silicon concentration of an etching liquid E becomesexcessive, it is possible to quickly suppress the silicon concentrationof the etching liquid E to a predetermined concentration. Then, whenstep S110 and step S111 are ended, the process is completed.

FIG. 16 is a flow chart illustrating a processing procedure of a mixingprocess and a substrate processing according to the third modificationof the embodiment. First, the controller determines whether a wafer W isimmersed in the processing bath 31 (step S201).

Then, when the wafer W is not immersed in the processing bath 31 (stepS201, No), for example, when a liquid exchange process is performed inthe processing bath 31, the controller performs a mixture liquidgeneration processing of generating a mixture liquid M by the mixingdevice 10 (step S202).

Next, the controller controls the heater 17 so as to perform a heatingprocessing of heating the generated mixture liquid M (step S203). Inthis step S203, the controller heats the mixture liquid M to, forexample, a predetermined temperature of less than 100° C.

Next, the controller controls the mixing device 10 and the liquidsending path 22 so as to perform a mixture liquid sending processing ofsending the mixture liquid M to the processing bath 31 (step S204).Then, the controller controls the silicon solution supply 25 so as toperform a silicon solution supply processing of supplying a siliconsolution to the processing bath 31 (step S205).

Next, the controller controls the substrate processor 30 so as toperform a heating processing of heating the mixture liquid M to whichthe silicon solution has been supplied (step S206). In this step S206,the controller heats the mixture liquid M to which the silicon solutionhas been supplied to, for example, a temperature of about 165° C.

Finally, the controller controls the substrate processor 30 so as toperform an immersion processing of immersing the wafer W in the mixtureliquid M to which the silicon solution has been supplied (step S207),and completes the process.

Meanwhile, when the wafer W is immersed in the processing bath 31 (stepS201, Yes), for example, when the wafer W is etched in the processingbath 31, the controller performs a mixture liquid generation processingof generating the mixture liquid M by the mixing device 10 (step S208).

Next, the controller controls the back pressure valve 51 so as toperform a back pressure valve throttling processing of changing the backpressure valve 51 from a fully open state to a throttled state (stepS209).

Next, the controller controls the mixing device 10, the liquid sendingpath 22, and the return path 24 so as to perform a mixture liquidsending processing of sending the mixture liquid M to the processingbath 31 (step S210). In parallel with this mixture liquid sendingprocessing, the controller performs a mixture liquid dischargeprocessing of discharging the mixture liquid M containing the siliconsolution from the processing bath 31 (step S211).

Accordingly, it is possible to always maintain the silicon concentrationof the etching liquid E within the processing bath 31 at a constantlevel or less. Then, when step S210 and step S211 are ended, the processis completed.

The mixing method according to the embodiment includes a mixture liquidgeneration processing (step S102), and a silicon solution supplyprocessing (step S104). In the mixture liquid generation processing(step S102), a mixture liquid M is generated by mixing a phosphoric acidaqueous solution with an additive (a precipitation inhibitor) thatsuppresses precipitation of silicon oxide. In the silicon solutionsupply processing (step S104), a silicon-containing compound aqueoussolution (a silicon solution) is supplied to the generated mixtureliquid M. Accordingly, it is possible to properly perform an etchingprocessing by an etching liquid E containing a phosphoric acid aqueoussolution and a silicon solution.

The substrate processing method according to the embodiment includes amixture liquid generation processing (step S102), a silicon solutionsupply processing (step S104), and an immersion processing (step S107).In the mixture liquid generation processing (step S102), a mixtureliquid M is generated by mixing a phosphoric acid aqueous solution withan additive (a precipitation inhibitor) that suppresses precipitation ofsilicon oxide. In the silicon solution supply processing (step S104), asilicon-containing compound aqueous solution (a silicon solution) issupplied to the generated mixture liquid M. In the immersion processing(step S107), a substrate (a wafer W) is immersed in the mixture liquid Mto which the silicon solution has been supplied. Accordingly, it ispossible to properly perform an etching processing by an etching liquidE containing a phosphoric acid aqueous solution and a silicon solution.

In the substrate processing method according to the embodiment, when thesubstrate is immersed in the processing bath 31, the mixture liquid Mnot containing the silicon-containing compound aqueous solution (thesilicon solution) is supplied to the processing bath 31 (step S110).Along with this step S110, the mixture liquid M containing thesilicon-containing compound aqueous solution (the silicon solution) isdischarged from the processing bath 31 (step S111). Accordingly, whensilicon is eluted from a silicon nitride film within the wafer W and thesilicon concentration of the etching liquid E becomes excessive, it ispossible to quickly suppress the silicon concentration of the etchingliquid E to a predetermined concentration.

The substrate processing method according to the embodiment furtherincludes a heating processing (step S106) of heating the mixture liquidM to which the silicon-containing compound aqueous solution (the siliconsolution) has been supplied after the silicon solution supply processing(step S104). Accordingly, it is possible to perform an etchingprocessing on the wafer W by the etching liquid E heated to apredetermined temperature.

In the substrate processing method according to the embodiment, in themixture liquid generation processing (step S102), the mixture liquid Mis circulated through the circulation path 15 by the mixing device 10that includes the tank 14, and the circulation path 15 exiting from thetank 14 and returning to the tank 14. In the silicon solution supplyprocessing (step S104), the mixture liquid M is sent to the processingbath 31 from the liquid sending path 22 that is provided diverging fromthe circulation path 15. In the mixture liquid generation processing(step S102), the back pressure valve 51 provided in the circulation path15 on the downstream side of the diverging portion 15 c from which theliquid sending path 22 diverges is fully open, and in the siliconsolution supply processing (step S104), the back pressure valve 51 isthrottled. Accordingly, it is possible to secure the pressure requiredto return the mixture liquid M from the diverging portion 15 c to thetank 14 through the liquid sending path 22, the liquid sending path 22d, and the return path 24.

According to the present disclosure, it is possible to properly performan etching processing by an etching liquid containing a phosphoric acidaqueous solution and a silicon solution.

From the foregoing, it will be appreciated that various embodiments ofthe present disclosure have been described herein for purposes ofillustration, and that various modifications may be made withoutdeparting from the scope and spirit of the present disclosure.Accordingly, the various embodiments disclosed herein are not intendedto be limiting, with the true scope and spirit being indicated by thefollowing claims.

What is claimed is:
 1. A substrate processing apparatus comprising: aprocessing bath in which a substrate is immersed to be processed; amixer including a tank and a circulation path that exits from the tankand returns to the tank, the mixer configured to generate a mixtureliquid by mixing a phosphoric acid aqueous solution with an additivethat suppresses precipitation of silicon oxide; a liquid sending pathdiverging from the circulation path at a diverging portion of thecirculation path, the liquid sending path configured to send the mixtureliquid from the mixer to the processing bath; a silicon solution supplyconnected to at least one of the liquid sending path and the processingbath, and configured to supply a silicon-containing compound aqueoussolution to the mixture liquid supplied from the mixer; and a controllerconfigured to control the processing bath, the mixer, the liquid path,and the silicon solution supply, wherein a back pressure valve isprovided in the circulation path downstream from diverging portion, theliquid sending path includes a flow meter and a thermometer, the flowmeter configured to correct a flow rate of the mixture liquid based on atemperature of the mixture liquid measured by the thermometer, thecirculation path includes a return path that starts at the divergingportion where the liquid sending path including the flow meter divergesfrom the circulation path, and the return path continues downstream fromthe diverging portion to return to the tank, and the controller fullyopens the back pressure valve when the mixture liquid is generated whilecirculating the mixture liquid through the circulation path, andthrottles the back pressure valve when the mixture liquid is sent to theliquid sending path.
 2. The substrate processing apparatus according toclaim 1, wherein the circulation path includes a filter that filters themixture liquid, and a bypass flow path that bypasses the filter.
 3. Thesubstrate processing apparatus according to claim 1, wherein the mixerincludes a heater that heats the mixture liquid, and the controllercontrols the heater to set a temperature of the mixture liquid based onwhether to supply the silicon-containing compound aqueous solution tothe mixture liquid.
 4. The substrate processing apparatus according toclaim 1, wherein a plurality of mixers is provided for one processingbath, and each mixer of the plurality of mixers exclusively supplies themixture liquid to the one processing bath.
 5. The substrate processingapparatus according to claim 1, wherein a plurality of mixers isprovided for a plurality of processing baths, and the mixture liquid issequentially supplied to the plurality of processing baths that requiresupply of the mixture liquid starting from the mixer in which generationof the mixture liquid is completed.
 6. A substrate processing apparatuscomprising: a processing bath in which a substrate is immersed to beprocessed; a mixer configured to generate a mixture liquid by mixing aphosphoric acid aqueous solution with an additive that suppressesprecipitation of silicon oxide, wherein the mixer includes a tank, and acirculation path that exits from the tank and returns to the tank; aliquid sending path configured to send the mixture liquid from the mixerto the processing bath, wherein the liquid sending path is provideddiverging from the circulation path; a silicon solution supply connectedto at least one of the liquid sending path and the processing bath, andconfigured to supply a silicon-containing compound aqueous solution tothe mixture liquid supplied from the mixer; a back pressure valveprovided in the circulation path on a downstream side of a portion fromwhich the liquid sending path diverges; and a circuitry configured tocontrol the back pressure valve to be fully open while circulating themixture liquid through the circulation path so as to generate themixture liquid, and to be throttled when the mixture liquid is sent tothe liquid sending path.
 7. The substrate processing apparatus accordingto claim 6, wherein the circulation path includes a filter that filtersthe mixture liquid, and a bypass flow path that bypasses the filter. 8.The substrate processing apparatus according to claim 6, furthercomprising: a flow meter and a thermometer provided in the liquidsending path, wherein the flow meter corrects a flow rate of the mixtureliquid based on a temperature of the mixture liquid measured by thethermometer.
 9. The substrate processing apparatus according to claim 8,wherein the mixer includes a heater that heats the mixture liquid, andthe circuitry controls the heater to set a temperature of the mixtureliquid based on whether to supply the silicon-containing compoundaqueous solution to the mixture liquid.
 10. The substrate processingapparatus according to claim 8, wherein a plurality of mixers isprovided for one processing bath, and each mixer of the plurality ofmixers exclusively supplies the mixture liquid to the one processingbath.
 11. The substrate processing apparatus according to claim 8,wherein a plurality of mixers is provided for a plurality of processingbaths, and the mixture liquid is sequentially supplied to the pluralityof processing baths that require supply of the mixture liquid startingfrom the mixer in which generation of the mixture liquid is completed.